> Could you point me at some info on this one (-ftree-vectorize)? It came
> up on the amd64 list a week or so ago, when someone asked what I thought
> of it and why I didn't have it in my cflags (which I had just explained).
> I said I didn't know enough about it to make a case either way, and as
> such, didn't choose to use it. However, after a bit of discussion, I
> decided to add it to my cflags on a very experimental basis. I haven't
> experienced any issues with it, but then I haven't done any major
> compiling since then either, only the routine updates.

http://tinyurl.com/l75we
They've fixed quite a few of the ICE's since last I looked, though
there's more than a couple that went in after 4.1.1. 4.2 is a little
better, but I'm having enough trouble getting it to build things
properly _without_ using any fancy flags right now. ;p
See http://tinyurl.com/rt3aa for some real-world examples.

> Or does the problem not necessarily apply to amd64? Even knowing that
> would be useful. I simply don't know anything much at all about it, beyond
> a generally vague idea that it means using mmx/sse/whatever vector
> instructions to parallelize loops.

I'd say that there's more ICE's on i686-pc-linux-gnu than
x86_64-*-linux-gnu, but there's still enough. Luckily Halcy0n was
really good for reducing testcases and pushing them upstream, so a lot
of these issues got fixed at the source.
--de.